How long must you attend college to become an anesthesiologist?
There are actually two different options. You can attend a 2 year college and receive an Associate Degree in Nursing Or you can attend a 4 year college and receive a Bachelor of Science in Nursing. The difference in the end can be the pay. Also the RN's with BSN are more likely to have a managerial or leadership position in a Health Care Setting.
You aren't, technically speaking, required to attend college at all to become an astronomer. However, if you want to be hired as an astronomer and get paid as opposed to doing it as a hobby and buying all your own equipment, you should expect to minimally get a 4-year bachelor's degree in Astronomy or possibly Physics.